Farmer ants draft parasite ants as mercenaries

Farmer ants draft parasite ants as mercenaries

Farmer ants can recruit parasites to battle for them, much like medieval cities sometimes kept expensive contingents of mercenary soldiers to ward off invaders, researchers say.

The finding, illustrated in a video of the mercenary ants, highlights that parasites might not always be a bad thing, underscoring the complex relationships between species in nature, investigators added.

Scientists investigated ants in Panama named Sericomyrmex, which raise fungus in gardens. The farmer ants are regularly beset by parasitic ants named Megalomyrmex. Queens of Megalomyrmex stealthily enter and colonize the gardens of Sericomyrmex and can feed on their offspring and their fungus for years. They also clip the wings of the virgin queens of the farmers, hampering the spread of Sericomyrmex colonies.

Ant soldiers

Evolutionary biologist Rachelle Adams at the University of Copenhagen had studied Megalomyrmex for more than a decade when she noticed they were remarkably common compared with other parasitic species, at times making up than 80 percent of some host populations.

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The research team also discovered the chemical warfare Megalomyrmex conducts works in an unexpected way.

“The raider ants attacked by the Megalomyrmex were often attacked by their own nest mates,” Adams said. “This suggests that the guest ant venom disrupts the recognition system of the raiders, causing sisters to attack and kill one another.”

Symbiotic relationships between species “are more complex than what we might first expect,” Adams said.

Parasitism evolving into symbiosis – as it can do where balance is achieved through natural selection.